I. Field
The present disclosure relates generally to wireless communication, and more particularly to implementing a composite channel tree for resource assignments.
II. Background
Wireless communication systems are widely deployed to provide various types of communication content such as voice, data, and so on. These systems may be multiple-access systems capable of supporting communication with multiple users by sharing the available system resources (e.g., bandwidth and transmit power). Examples of such multiple-access systems include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, 3GPP LTE systems, and orthogonal frequency division multiple access (OFDMA) systems.
Generally, a wireless multiple-access communication system can simultaneously support communication for multiple wireless terminals. Each terminal communicates with one or more base stations via transmissions on the forward and reverse links. The forward link (or downlink) refers to the communication link from the base stations to the terminals, and the reverse link (or uplink) refers to the communication link from the terminals to the base stations. This communication link may be established via a single-in-single-out, multiple-in-signal-out or a multiple-in-multiple-out (MIMO) system.
A MIMO system employs multiple (NT) transmit antennas and multiple (NR) receive antennas for data transmission. A MIMO channel formed by the NT transmit and NR receive antennas may be decomposed into NS independent channels, which are also referred to as spatial channels, where NS≦min{NT, NR}. Each of the NS independent channels corresponds to a dimension. The MIMO system can provide improved performance (e.g., higher throughput and/or greater reliability) if the additional dimensionalities created by the multiple transmit and receive antennas are utilized.
A MIMO system supports a time division duplex (TDD) and frequency division duplex (FDD) systems. In a TDD system, the forward and reverse link transmissions are on the same frequency region so that the reciprocity principle allows the estimation of the forward link channel from the reverse link channel. This enables the access point to extract transmit beamforming gain on the forward link when multiple antennas are available at the access point.
Resource assignments in such MIMO systems and other wireless communication systems generally rely on a binary channel tree for assignment. The binary tree offers acceptable encoding efficiency for an assignment process that utilizes a small number of bits (e.g., six bits or less). However, binary channel tree resource assignment experience granularity issues and fragmentation issues.
In terms of granularity, assignment sizes are limited to powers of (e.g., 2, 4, 8, 16, 32, 64, 128 and the like). Thus, if assignment only requires 100 resources, for example 100 carriers, the binary channel tree requires that 128 resources be assigned or multiple assignments be made to account for the 100 required resources. In either instance, in which 128 resources would be assigned or multiple assignments made, the procedure is economically inefficient.
In terms of fragmentation, narrowband assignments can render the available resources unaddressable with a single channel identification. Thus, if an assignment requires 256 resources, for example 256 subcarriers, the assignment would generally require a high node assignment on the binary channel tree. However, if a previous assignment has been assigned a base node then all the parent nodes that include the base node are unaddressable. Thus, fragmentation issues result in inefficient assignment of network resources.
In view of at least the above, a need exists for a resource assignment system and/or methodology for effectively and efficiently assigning resources in a wireless communication system. The desired system and/or methodology should overcome issues related to fragmentation in an assignment based solely on a binary node channel tree and minimize the issues related to granularity associated with assignment based solely on a binary node channel tree